Ответ:

  1. \(\frac{16\cdot10\cdot18}{70\cdot12\cdot24}=\frac{2880}{20160}=\frac{1}{7}\).
  2. \(\frac{15\cdot35\cdot21}{75\cdot49\cdot14}=\frac{11025}{51450}=\frac{3}{14}\).
  3. \(\frac{8\cdot7+5\cdot7-2\cdot7}{121}=\frac{56+35-14}{121}=\frac{77}{121}=\frac{7}{11}\).

Ответ: а) \(\frac{1}{7}\); б) \(\frac{3}{14}\); в) \(\frac{7}{11}\).